Recently, the housings of portable terminal devices typified by cellular phones, smartphones, personal digital assistants (PDAs), electronic book readers, and the like have been required to have reduced dimensions and weight from the viewpoint of compactness and lightness. Accordingly, demands have arisen for more compact antenna apparatuses. It has also been required to allow a single portable terminal device to communicate with a plurality of radio systems using different frequency bands.
Under the circumstances, conventionally, for example, a multifrequency antenna apparatus has been proposed, which has the second antenna element formed from a monopole element provided at a position near the feed point of the first antenna element formed from, for example, a folded element with a stub in a direction opposite to the first antenna element. This multifrequency antenna apparatus achieves size reduction of the antenna apparatus by covering a low-frequency band (for example, the 800-MHz band) with the folded element with the stub and also covering a high-frequency band (for example, the 2-GHz band) with the monopole element.
However, further reducing the distance between the folded element and the monopole element to further miniaturize (reduce the height and width) the antenna apparatus will decrease the impedance of the monopole element and make it impossible to obtain satisfactory antenna characteristics.